Dipyridamole in vitro suppresses the generation of T-cell cytotoxic functions: synergistic activity with cyclosporine

The pharmacological activity of dipyridamole has been related to its ability to increase intracellular cAMP. Elevated cAMP concentrations can tone down T-cell effector functions. The aim of this study was to evaluate the dipyridamole effect in vitro on the generation of alloreactive cytotoxic and lymphokine-activated killer cells in normal T-cell subpopulations. Dipyridamole suppressed T-cell cytotoxic functions in a dose-dependent way. The kinetics of suppression showed that dipyridamole prevented the first step of cytotoxicity, i.e. activation of the lytic program following allogeneic or interleukin-2 stimulation. The ability of dipyridamole to interact with the immunosuppressive activity of cyclosporine was also investigated. By itself, cyclosporine suppressed the generation of alloreactive cytotoxicity, but not the generation of lymphokine-activated killer cells. A synergistic immunosuppressive activity between dipyridamole and cyclosporine was observed on the generation of alloreactive cytotoxic T lymphocytes.